This invention relates to a spinal implant, particularly an implant adapted to encourage bone ingrowth resulting in stabilization of adjacent vertebrae and reduction of back pain. The invention is also concerned with a method of implantation and an apparatus for placement of the spinal implant between adjacent vertebrae.
Many types of intervertebral implants are known in the art. For example, U.S. Pat. No. 3,867,728 discloses a prosthesis for spinal repair which comprises a laminated core element made from an elastomer, such as silicone rubber or polyurethane, and fabric-reinforced elastomer.
U.S. Pat. No. 4,309,777 discloses an artificial intervertebral disc comprising upper and lower disc portions having a plurality of springs positioned therebetween and spikes extending outwardly from said disc portions for engagement with adjacent upper and lower vertebrae.
U.S. Pat. No. 4,349,921 discloses an intervertebral disc prosthesis comprising a shaped body of substantially rigid, non-porous, biologically compatible material. The surfaces of the disc have characteristics to produce a "friction-fit".
U.S. Pat. No. 4,479,491 discloses an intervertebral stabilization implant including an elongated central portion and a pair of reverse wings each disposed at an angle with respect to the elongated central portion.
Other types of spinal stabilizers, for example fixator plates and rods, are also known in the art, but these are not intervertebral implants as that term is used herein.
It has now been found that improved stabilization is achieved by an implant which is adapted to encourage bone ingrowth and thereby stabilizes adjacent vertebrae by fusing said vertebrae to the implant.